383 needs more power

First post since 2018? Welcome to the site! I would try tuning what you have. I would start with this list:
  1. make sure throttle is coming open all the way
  2. check initial timing
  3. check total timing
  4. check compression
  5. make sure all cylinders are firing (yes, I've seen a dead plug wire)

Exactly.

But no! Lets throw heads and a stroker crank on! geez.